This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Branched-Chain-Amino-Acid Transaminase enzymes (IlvE) are part of the bacterial biosynthetic pathway for the denovo synthesis of this class of amino acids. These are dietary essential amino acids for humans, making the bacterial transaminase a good drug target for this unique bacterial pathway. The tuberculosis (Tb) Ilve protein has been crystallized in hopes that the structural understanding of this enzyme will lead to potential new therapies for the treatment of this disease. The crystal strucuture will complement our kinetic work on this enzyme and a through understanding of this key component of this essential bacterial biosynthetic pathway.